Studies on Alloys 
119 
tion goes on in a perfectly clear solution and the end point is 
sharply defined and unmistakable. An analysis gave the fol- 
lowing results: 
Copper 
Lead. . 
Tin.... 
Zinc. . . 
62.33 
1 .66 
T3 
35.29 
99.81 
The amounts of iodine solution required for the estimation of 
the tin in two samples calculated to 4 grams per sample? were as 
follows : 
Modified method? 6.82 cc. 6.88 cc.? as compared with Mr. Low’s 
method? 133.cc.? I75mc. and 159.cc. 
II. BABBITT ANALYSIS BY THE METHOD OF W. H. LOW. 
The method followed in this work was that of Mr. W. H. Low, 
published in the Journal of the American Chemical Society for 
January 1907, with some slight modifications that seemed to be 
demanded by the nature of the work. It was in connection with 
this work that the application of the method to alloys containing 
large amounts of copper, was tried. The criticism of the method 
for such alloys appears elsewhere in these pages. 
Below appears a detailed statement of what was done in apply- 
ing the method. Standard solutions of ammonium molybdate, 
potassium permanganate, iodine and sodium thiosulphate were 
prepared. These were made and standardized as appears below. 
1 . Ammonium molybdate. About 9 grams of the dry salt were 
dissolved dn each liter of water. This solution was then stand- 
ardized by titrating it against thoroughly dried, pure lead sulphate. 
The latter was dissolved in ammonium acetate, diluted to 250 cc., 
acidified with acetic acid, heated to boiling and titrated, using tan- 
nin as an indicator. The tannin solution was made by dissolving 
tannin in about 300 parts of water. The value of the molybdate 
solution was calculated as follows: 
Weight of PbS04 taken 
Weight of lead in {a) = («) X .68292 
Volume of molybdate solution used 
I cc. of molybdate = (h) (c) 
= .xxxx (a) 
= .xxxx (h) 
= .xxxx (c) 
= .xxxxx g. Pb. 
